Method of operating an impact comminutor

ABSTRACT

An impact comminutor has a rotor element and movable comminuting elements mounted outwardly and circumferentially spaced about the rotor element. Material to be comminuted is admitted into the apparatus to thereby undergo comminution into larger and smaller fractions and in this shape leave the machine. The comminuted material is then subjected to measurements to determine the proportion of a selected one of these fractions with reference to the sum of all other fractions, and the speed of rotation of the rotor element and/or the positioning of the comminuting elements with reference to one another and with reference to the rotor element are adjusted as a function of the measured value thus obtained.

United States Patent 1 Motek et al.

[ METHOD OF OPERATING AN IMPACT COMMINUTOR [75] Inventors: Herbert Motek, Essen-warden; Jakob Jobkes, Muenster-Westfalen, both of Germany [73] Assignee: llaieinag, Hartzerlileinerun gs md Zement-Maschinenbau-Gesellschaft M.B.H., Munster, Germany [21] Appl. No.: 133,973

[30] Foreign Application Priority Data April 17, 1970 Germany ..P 20 18 496.7

[56] References Cited UNITED STATES PATENTS Barrot ..24l/37 [4 1 Feb. 13, 1973 6/1942 Hartshom ..24l/l89 R X 10/1956 West ..24l/189 R [5 7] ABSTRACT An impact comminutor has a rotor element and movable comminuting elements mounted outwardly and circumferentially spaced about the rotor element. Material to be comminuted is admitted into the apparatus to thereby undergo comminution into larger and smaller fractions and in this shape leave the machine. The comminuted material is then subjected to measurements to determine the proportion of a selected one of these fractions with reference to the sum of all other fractions, and the speed of rotation of the rotor element and/or the positioning of the comminuting elements with reference to one another and with reference to the rotor element are adjusted as a function of the measured value thus obtained.

9 Claims, 1 Drawing Figure PATENIED FEB 1 3 I975 METHOD OF OPERATING AN IMPACT COMMINUTOR BACKGROUND OF THE INVENTION The present invention relates generally to a comminuting method and more particularly to a method of operating an impact comminutor.

In recent years the use of so-called impact comminutors has strongly increased in all areas of comminution where the application of this type of equipment is feasible. The reason for this increase in popularity of impact comminutors is that they are capable of comminuting-that is reducing from larger size to smaller sizelarge quantities of material in a relatively small and inexpensive plant. The extent to which the materials are comminuted and reduced in size, is substantially better than if the same materials were comminuted in the heretofore common machines, such as jawbreaker or rotary crusher machines.

In impact comminutors the comminution of the material is primarily effected by the contact portions or impact bars provided on the single or several rotors which rotate within the machine, in conjunction with the break-up plates or rebound plates. The material contacts the rotating rotor or rotors and is flung off the same against the breakup plates. The wear in such apparatus is primarily concentrated on the contact or impact portions mounted on the rotors, because they are of relatively small size so that their configuration and size changes relatively rapidly due to wear resulting from constant contact with the material being comminuted. This makes it necessary to exchange these contact portions relatively rapidly. Furthermore, the comminuting circumstances also change after a relatively brief operating time due to a rounding of the edges of the contact portions, again resulting from wear, and the circular area surrounding the circumference of the rotor and within which material is contacted by the contact portions projecting from the circumference of the rotor, varies-that is increases as the materal of the contact portions wears away-so that the circumferential speed of the edges on the contact portions on the rotor-which is determinative for the proper comminution-should also vary concomitantly with the wear. Finally, the space between the outermost edges of the rotating contact portions and the break-up plates which are radially outwardly'spaced from and distributed circumferentially of the rotor and against which the materialto be comminuted is flung, increases constantly due to wearing-away of the contact portions. As the space increases, however, the material can leave the comminuting chamber prematurely. The result of all of this is the fact that the degree of comminution of the material in impact comminutors worsens constantly, so that uniform comminution can be obtained only by constant regulation of the operation of the comminutor to make up for such worsening.

SUMMARY OF THE INVENTION It is, accordingly, an object of the present invention to overcome these disadvantages.

More particularly, it is an object of the present invention to provide an improved method of operating an impact comminutor so that these disadvantages no longer obtain.

A concomitant object of the invention is to provide such an improved method which assures that the initially selected degree of comminution-that is size and width of different fractions in the comminuted material-will be automatically maintained at all times.

In pursuance of the above objects and others which will become apparent hereafter, one features of the present invention resides in a method of operating an impact comminutor having a rotor element and movable comminuting elements mounted outwardly and circumferentially spaced about the rotor element. The novel method comprises, briefly stated, the steps of admitting material to be comminuted into the comminutor so as to undergo comminution into larger and smaller portions prior to leaving the comminutor. The proportion of one of the fractions with reference to the sum of all other fractions in a quantity of comminuted material is measured, and at least one of the elements is adjusted with reference to the other element or elements as a function of the thus-measured value.

This means that the speed of rotation of the rotor or rotors may be varied, and also that the spacing of the comminuting elements-cg, break-up plates-with reference to the circumference of the rotor as well as with reference to one another may be changed, either in unison or individually and, if desired, in predetermined sequence.

According to a further concept of the invention the variation of several values influencing the degree of comminution may be preselected in its sequence and in its relationship by suitable electronically controlled sequencing means. Contactless (i.e. non-contact-making) sensors may limit the maximum displacement of the various movable elements, particularly with reference to their approach towards the circumference of the rotor or rotors.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims.

The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific ernbodiments when read in connection with the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING The single FIGURE is a somewhat diagrammatic side-elevational view, illustrating an impact comminutor whose operation is to be controlled in accordance with the present method.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the FIGURE we have illustrated diagrammatically an impact comminutor, no attempt having, however, been made to show all details of such a machine. Impact comminuters are well enough known for those skilled in the art to be able to understand the present invention from the diagrammatic illustration represented in the FIGURE.

The comminutor has a housing 1 and in this embodiment a single rotor 2, which is provided on its circumference with the contact portions 3 which may be in form of strip-shaped elements or the like. In any case,

the outermost edges of these contact portions describe about the circumference of the rotoras the latter rotates with the contact portions 3-a circular path 4. The rotor 2 is driven in rotation by a suitable electromotor for instance via a continuously variable gear drive 5.

Mounted about the rotor circumferentially and radially spaced therefrom is a plurality of breaker plates 6. However, a single such breaker plate could also be utilized. In any case, in the illustrated embodiment the lower edges of the breaker plate 6 define with the circle 4 a gap a. In order to obtain certain grain configurations it is also possible to provide a so-called grinding path 8 which surrounds a portion of the circumference of the rotor 2 and may be configurated as a grate or the like, if desired. This is already known. For the positioning of the element 8 the gap b between the element 8 and the circle 4 is determinative.

The breaker plates 6 and the element 8, if the latter is provided as in the illustrated embodiment, can be displaced with reference to the rotor 2 by means of hydraulic cylinders 7 which need not be discussed or described in more detail because they are entirely conventional.

The material to be comminuted is introduced in known manner via a conveying device 10 into the inlet 11 of the impact comminutor, and after being comminuted leaves the comminutor through the outlet 12.

A diverting member 12' is provided which periodically acts to divert a portion of the comminuted material onto a screen 13 which may be so constructed as to have several layers of different mesh superimposed one upon the other. At the outlet end of the screen 13 there are provided weighing devices 14 and 15, such as scales, which act upon an indicating device 16 coupled with them and which indicates the difference of the quantities of comminuted material received by the devices 14 and 15, respectively. It will be clear that the construction of the screen 13 is such that a fraction of a certain grain size is permitted to go to one of the weighing devices (either 14 or 15) whereas the remaining fractions go to the respectively other weighing device. Thus, the proportion of the preselected single fraction which serves as an indicator of the degree of comminution to the sum of the remaining fractions is determined by comparing the weights, and the result may be utilized either in form of an electronic value or a hydraulic impulse and be forwarded via the hydraulic unit 9or a suitable electric unit which may be used in its place-to the gear drive 5 or to the hydraulic cylinders 7. In other words, the measured value will be used to vary the speed of rotation of the rotor 2 and/or to displace the components 6 and/or 8 with reference to the rotor 2. This serves to maintain the degree of comminution constant in that it automatically compensates for wear of the portions 3.

The indicator device 16 constantly provides an indication of the proportion of the selected fraction with reference to the total quantity of comminuted material. It is well known that this value-given the same machine and the same mix of material entering through the inlet 1lis determinative of the total grain size composition ofthe comminuted material.

With respect to the indicator device 16, it is pointed out that the indicator thereof may act directly or via a proportionately variable small electromotor upon a switching device of the type which is for instance available under the designations BSW 499, BSW 502 and BSW 496 from the Balluff KG of Neuhausen, Germany. Such a switching device may be incorporated in unit 9 and utilizes adjustable cams which can be set to preselect the sequence and time intervals at which changes in the operation and/or position of the elements 5, 6 and 8 are to take place. The cams act upon limit switches which in turn act upon a hydraulic device forming part of unit 9 and which may be of the type available from the E. A. Storz K.G. of Tuttlingen, Germany.

If desired, the control of elements 5, 6 and 8 can also be effected completely electrically, i.e. without the hydraulic device. In this case the signals from the limit switches are supplied via known relays to electromotors having axially displaceable spindles, such as are available under the designation Elektro-Zylinder from the Raco-Elektro-Maschinenbau GmbH of Schwelm, Germany, and which replace the elements 7.

The devices l4, l5 and 16 measure simultaneously the two separate material quantities which they respectively receive, namely the preselected fraction and the remaining fraction of the quantity of comminuted material which is diverted to them by the component 12. These measurements are compared with one another and the result obtained. Via electronic or electrical impulses the thus obtained value acts upon the device 9 which in accordance with a preset value controls the operation and/or positioning of the drive 5, the components 6, and the device 8 in preselected sequence.

If a change takes place in the proportion of the preselected fraction with reference to the other fractions due to wearing away of the portions 3, this proportional change is detected by the devices 14, 15 and 16 and, in order to maintain the preselected mix of comminuted fractions these devices will forward impulses to the unit 9 in order to obtain the aforementioned control functions, that is the variation in the speed of rotation of the rotor, displacement of the components 6, or of the unit 8, singly or in the various combinations. Because all of this takes place without requiring manual operations by personnel provided for this purpose, the control of the machine is automatic, which is desirable.

The scales or weighing devices 14 and 15 in the illustrated embodiment are in form of two guide members which are journalled and which, depending upon the weight acting upon them, will because displaced to different extents from their normal rest position, thereby exerting pressure upon balancing weights, springs or other elements provided for this purpose. They can be replaced, however, with other devices, for instance with conveyortype scales, such as manufactured by the Haasler GmbH of Lengereich, Germany.

In the illustrated embodiment the device 9 is a hydraulic unit including electrically controlled hydraulic valves which are controlled by the impulses derived from the devices 14, 15 and 16 and in accordance with this control supply oil to the devices 5 and 7 via a nonillustrated hydraulic pump.

it will be appreciated that maintaining a preselected particle size and mix in the comminuted material is very often highly important, for instance with reference to specifications, which in many countries are established by governmental agencies-for materials to be used in road construction. Evidently, if the mix can be maintained in this manner, this is much preferable and considerably less expensive than if an integration of the desired or necessary mix from individual fractions which must be weighed and admixed, has to be carried out. The present invention also avoid quite clearly the necessity for maintaining stocks of different sized fractions for subsequent admixture.

Because the comminution of the material depends primarily upon the circumferential speed of the contact portions 3 of the rotor 2, which substantially decreases as the material of the contact portions 3 wears away, it is advantageous that signals which are originated due to variations detected in the mix by the devices 14, and 16 vary first the speed of rotation of the rotor 2 by issuing a command to the gear drive 5, and that only after a requisite number of rotations per minute is obtained in this manner, the other elements such as the elements 6 and 8 are moved with reference to the circumference of the rotor, that is towards the same. Non-illustrated non-contact-making sensors of well known construction may be employed to assure that the components 6 and 8 cannot move so close to the rotor as to come within the region of the circle 4, where they would be contacted by the portions 3 and risk resultant damage.

We may utilize ultrasonic waves or isotope radiation for the continuous monitoring of wear on the contact portion and on other components. Devices for this purpose are known and are, for instance, available from the Endress and Hauser GmbI-l & Co. of Maulburg, Germany. Signals originating in these devices can also be supplied by the non-contact-making sensors which may be of the type available from Balluff KG of Neuhausen, Germany under the designation BES Kompaktschalter.

By resorting to the present invention a constancy of the mix of grain size fractions in the comminuted material is obtained which is independent of any wear on components of the apparatus itself, particularly wear of the portions 3.

It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of applications differing from the types described above.

While the invention has been illustrated and described as embodied in a method of operating an impact comminutor, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims.

We claim: l. A method of operating an impact comminutor having a rotor element rotatable at variable rates of speed which can be increased, and comminuting elements mounted circumferentially spaced about the rotor element and whose positions relative to said rotor element can be varied, both in response to wearingaway of the respective elements, comprising the steps of admitting material to be comminuted into said comminutor so as to undergo comminution into larger and smaller fractions prior to leaving said comminutor; measuring the proportions of one of said fractions to the sum of all of said fractions in a quantity of comminuted material; and compensating for wearing-away of the respective elements by at least increasing the rate of speed of said rotor element as a function of the thus-measured value.

2. A method as defined in claim 1, wherein the step of compensating further comprises displacing at least one of said comminuting elements with reference to the circumference of said rotor element.

3. A method as defined in claim 1, wherein the step of compensating is effected in automatic response to said measured value.

4. A method as defined in claim 1, wherein the step of compensating further comprises displacing said comminuting elements simultaneously with reference to the circumference of said rotor element as well as with reference to one another.

5. A method as defined in claim 1, wherein the step of compensating comprises displacing said comminuting elements sequentially with reference to the circumference of said rotor element as well as with reference to one another.

6. A method as defined in claim 2, said comminuting elements being movable towards and away from the circumference of said rotor element; and further comprising the step of sensing the approach of comminuting elements being displaced toward said rotor element, and limiting such approach to a predetermined distance from said rotor element.

7. A method as defined in claim 6, wherein the step of sensing comprises contactless sensing.

8. A method as defined in claim 1, wherein the step of measuring comprises weighing said one fraction and weighing all others of said fractions separate from said one fraction.

9. A method as defined in claim 8, wherein the step of measuring further comprises comparing the weight of said one fraction with the weight of all others of said fractions. 

1. A method of operating an impact comminutor having a rotor element rotatable at variable rates of speed which can be increased, and comminuting elements mounted circumferentially spaced about the rotor element and whose positions relative to said rotor element can be varied, both in response to wearing-away of the respective elements, comprising the steps of admitting material to be comminuted into said comminutor so as to undergo comminution into larger and smaller fractions prior to leaving said comminutor; measuring the proportions of one of said fractions to the sum of all of said fractions in a quantity of comminuted material; and compensating for wearing-away of the respective elements by at least increasing the rate of speed of said rotor element as a function of the thus-measured value.
 2. A method as defined in claim 1, wherein the step of compensating further comprises displacing at least one of said comminuting elements with reference to the circumference of said rotor element.
 3. A method as defined in claim 1, wherein the step of compensating is effected in automatic response to said measured value.
 4. A method as defined in claim 1, wherein the step of compensating further comprises displacing said comminuting elements simultaneously with reference to the circumference of said rotor element as well as with reference to one another.
 5. A method as defined in claim 1, wherein the step of compensating comprises displacing said comminuting elements sequentially with reference to the circumference of said rotor element as well as with reference to one another.
 6. A method as defined in claim 2, said comminuting elements being movable towards and away from the circumference of said rotor element; and further comprising the step of sensing the approach of comminuting elements being displaced toward said rotor element, and limiting such approach to a predetermined distance from said rotor element.
 7. A method as defined in claim 6, wherein the step of sensing comprises contactless sensing.
 8. A method as defined in claim 1, wherein the step of measuring comprises weighing said one fraction and weighing all others of said fractions separate from said one fraction. 